#define _CRT_SECURE_NO_WARNINGS 1

#include<iostream>
#include<string>
using namespace std;

int main()
{
	int n;
	string s;
	string s1, s2;

	cin >> n;
	cin >> s1 >> s2;

	int prev1 = -1, prev2 = -1, ret = 0x3f3f3f;
	for (int i = 0; i < n; i++)
	{
		cin >> s;
		if (s1 == s)
		{
			if (prev2 != -1)
			{
				ret = min(ret, i - prev2);
			}
			prev1 = i;
		}
		else if (s2 == s)
		{
			if (prev1 != -1)
			{
				ret = min(ret, i - prev1);
			}
			prev2 = i;
		}

	}

	if (ret == 0x3f3f3f) cout << -1 << endl;
	else cout << ret << endl;
	return 0;
}